For instance for packaging semiconductor chips and for connecting the packaged semiconductor chip to a printed circuit board, a number of electric contacts has to be made. The ability to provide more and more I/O interconnections to a die (bare chip) that is increasingly shrinking in size is an important issue. In addition, the smaller size of the package contributes as much to the miniaturization of cellphones and other handheld devices as the shrinking of the semiconductor circuits.
WO 02/13253 discloses a method of producing a female microconnector for connection to a microcomponent having a corresponding male connector, the method comprising the steps of depositing a first layer on a substrate, removing a selected portion of the first layer, and removing a selected portion of the substrate to define a recess having an opening in the substrate with one or more portions of the first layer partially extending over the opening of the recess, the material and thickness of the first layer selected such that when a corresponding male connector is inserted into the recess, the one or more portions of the first layer extending over the opening of the recess flex to hold the male connector in the desired position within the recess, wherein the selected portion of the substrate is removed by a first etching process using a first etchant to undercut the first layer, the etch period of the first etching process being selected to etch a first width sufficient to allow the first layer to flex, and a second etching process using a second etchant different to the first etchant to etch to a second width to undercut the first layer, the etch period of the second etching process being selected so that the second width is less than the first width, wherein the etch rate of the second etching process normal to the plane of the first layer is greater than the etch rate parallel to the plane of the first layer.
However, conventional connection techniques do not allow to provide a sufficient number of contacts when pieces to be connected become smaller and smaller.